The problem is she is too extroverted for her own good, while Tomoko is introverted by necessity. Both typically have the same mindset but over time got nurtured differently by their environment. Fang likes to shit talk about everyone to other people in her circle of """"friends"""". While Tomoko thinks everyone she does not interact with is shallow, self-absorbed shitty popular people.
The table is slowly turning as Tomoko have been so secluded to herself throughout most of her formative years in middle/high school. She created a mystique about her with having interest in degenerate things. Fang has been pretty opposite as in her only interesting feature is being a gossipy bitch.